Road vehicles are known which include driven rear axles. The rear axles include a crown wheel and pinion and differential. The pinion is driven via a drive shaft or the like connected to a prime mover such as an engine. The pinion and drive shaft rotate about a longitudinal axis of the vehicle. The pinion together with the crown wheel enables the crown wheel to rotate about an axis which is laterally orientated relative to the vehicle. The crown wheel drives a differential mechanism which drives a right and left hand drive shaft (known as half shafts). The right hand drive shaft drives a right hand wheel rotatably mounted to the axle and the left hand drive shaft drives a left hand wheel rotatably mounted to the axle. In this way the vehicle can be driven over the ground.
The crown wheel, pinion and differential assembly require lubrication and cooling and a fluid, typically an oil, will perform this dual function. The crown wheel, pinion and differential assembly are mounted on a differential carrier assembly that is fixed to the axle housing by bolts. When the vehicle is driven, the axle housing and the differential carrier assembly experience vertical, longitudinal and torsional forces, which cause deformation of the axle housing and the differential carrier assembly. This causes leakage of the fluid from the resulting gaps between the differential carrier assembly and the axle housing.
It is known to include gaskets or sealants between the differential carrier assembly and the axle housing in order to prevent leakage, however leakage of fluid still occurs. This is a particular problem for lightweight axle housings, for which the reduced weight results in greater deformation.
The leakage of fluid from the axle housing results in high warranty costs and so an axle assembly with improved resistance to vertical, longitudinal and torsional forces is required.